Ken Livingstone, who has been suspended from the Labour party for a further year, but not expelled, over his comments that Hitler supported Zionism.Photograph: Lauren Hurley/PA

In modern times it is not Labour’s normal practice to belittle the views of those who say they have been victims of racial prejudice, to query their motives and to reject the premises of their complaint. For good reasons, the party’s default position has become a determined readiness to define racism as its victims would like it to be defined. But there is arguably now an exception to this basic ethos of sensitivity: Jews. When the allegation is antisemitism and a Labour politician is being accused, the dynamic is often reversed. A presumption can take hold that the offence cannot have been committed because the left is opposed to all racism.

Warped logic then unfolds: anti-racists cannot be guilty of prejudice against Jews, so it follows that Jewish complaints about prejudice are dishonest. The offence is pushed back on to the people who thought they had been offended. It is reconfigured as a plot to discredit political foes; part of a hidden agenda connected to Israel-Palestine. This argument then feeds the idea that an accusation of antisemitism is a weapon deployed by Jews (usually for decorum’s sake recast as “Zionists”) for nefarious purposes. Thus the ancient racist narrative of kosher conspiracy and shadowy machination thrives even among those who imagine they are policing racism.

This pattern has played itself out in public view in the case of Ken Livingstone’s disciplinary hearing. He was charged with bringing the party into disrepute over remarks he made last year – and has repeated subsequently – bundling Zionism and Nazism together in a mangled retelling of the 1930s, depicting Hitler’s supposedly more nuanced attitudes “before he went mad”. Even aside from the grotesque misreading of history, this kind of language is deeply offensive. Its rhetorical purpose is to imply intellectual or actual Jewish complicity with the perpetrators of their genocide, diminishing the crime of the Holocaust, and so undermine the moral foundations of the state of Israel.

Regardless of the rights and wrongs of Middle East conflict, that is a malicious way to handle matters of enormous complexity and cultural sensitivity. Mr Livingstone’s statements and unapologetic stances ooze contempt for the Jewish community. He has had every opportunity to moderate his language, rephrase his opinions and seek conciliation. Instead he has chosen gleeful defiance. He and his supporters have dismissed the row as a plot by enemies of Jeremy Corbyn, a smear campaign to discredit the leader and his friends.

Leave aside the internal wrangles that have tortured the opposition for the past two years. Set apart parallel arguments around Mr Corbyn’s opinions. Mr Livingstone’s case is egregious. The Labour leader on Wednesday recognised that his old comrade has caused “deep offence” that he has “failed to acknowledge”. Mr Corbyn has already committed Labour to a policy of “zero tolerance” on antisemitism. The party recognises definitions of the term that include vindictive revisionism of the Hitler-as-Zionist variety.

Every significant Jewish community body, every respectable historian, and every organisation that studies the Holocaust, to learn its lessons, has said that Mr Livingstone’s language is unacceptable.

Most Jews think it was hurtful. But a Labour committee has decided not to mind their pain. Mr Livingstone was found guilty of bringing the party into only minor disrepute, such that only suspension is required. Mr Corbyn has suggested further disciplinary action might be taken, although it is unclear of what kind.

How has it even come this far? Labour has heard every credible source say that one of its members has perpetrated and stoked prejudice against the Jewish community. It says his actions were wrong, but he is still in the party. An ugly conclusion is inevitable: Labour values Mr Livingstone’s membership over the fight against antisemitism. “Zero tolerance” was a lie.